This invention relates to hot air blower devices that output ionized air, and more specifically to such devices that produce ions withhout requiring high voltage ionization circuits.
Electrically powered hot air blowers have found widespread use, ranging from handheld household devices useful to dry wet hair, to large units that find industrial application. Typically 110-220 VAC is applied across a resistive Nichrome heating element to produce heat. An electric fan then blows heated air from the heating element in a desired direction, e.g., toward one""s head in a household hair dryer type device.
It can be advantageous in many applications to output ions along with the heated air. For example, in a hair dryer, ions can beneficially reduce static electricity in the hair that is being dried, to hasten the grooming process. In hair dryer and other applications, an outflow of ions can be useful to sterilize or deodorize. In industrial applications, ions can be used to neutralize electrical charge, for example in a CMOS semiconductor fabrication site.
Applicants"" U.S. Pat. No. 5,975,090 (November 1999) entitled xe2x80x9cIon Emitting Grooming Brushxe2x80x9d disclosed a cold air hair brush that emits ions using a rather efficient high voltage ionizing circuit. However, by definition, such ion generating devices require circuitry to generate high voltage, typically many kilovolts. Further, such devices require an array of electrodes, across which high voltage is coupled. Although the resultant hair brush produces an outflow of ions, a simpler and less expensive approach is desired for a heating device, for example a hair dryer.
There is a need for a hot air blower device that not only outputs air that is heated, but air that contains ions. Preferably such device should function need for high voltage generation or special electrode arrays. Further such device should permit control over the net polarity of the output ions, preferably by a subtractive process.
The present invention provides such a device.
The present invention utilizes thermionic-like emission rather than high voltage to create an ion-producing environment within a hot air blower device, such as a hair dryer.
In a hot air blower device, the device housing contains a conductive coated heating element across which is impressed operating voltage preferably derived from 110 VAC. When sufficiently heated, the heating element appears to ionize air near the element, and in a preferred embodiment generates substantial amounts of positive ions. A motor operated fan within the device housing blows the heated air and thermally generated ions toward an exit port in the device housing. In the preferred embodiments, the coated heating element comprises first and second coils that be operated such that current flows through both elements in series (LO heat mode), or flows through only one coil (HI heat mode). A user-operable switch permits selecting the LO or HI modes of operation.
According to a preferred embodiment of the present invention, an optional electrically conductive grid or mesh is placed across the device exit port, in a position downstream from the thermally emitted ions. The housing further contains a rectifier circuit that in various embodiments provides half-wave or full-wave rectification of the input 110 VAC. The output of the rectifier circuit is coupled to the conductive grid or mesh such that a positive or a negative charge is impressed upon the grid.
The electric fan air flow forcibly moves the thermally generated ions toward the grid or mesh. Electrical charge coupled to the grid can influence the net charge at and downstream from the grid, and can influence the ionic content of the heated air that exits from the device. For example, if the grid is charged positively, some positive ions in the airstream will be slightly repelled but more negative ions will be neutralized by the charge on the grid, and are essentially subtracted from the output airflow. The result is that the fan created air flow will blow a net of positive ions through the outlet port of the device. If the grid were negatively charged, some negative ions in the airstream would be somewhat repelled and some positive ions would be neutralized by the charge on the grid. Thus, assuming that the nature of the heating coil will generate a net excess of positive ions, the net output flow of ions could still be positive, but with a somewhat reduced positive ion content compared to the above example. In the various embodiments, the result is that the heated air leaving the device exhaust port can have a net surplus of positive ions. If the heating element were coated to generate substantial negative ions, the output airflow could have a surplus of negative ions.
In the various embodiments, a user-operable switch enables high power (greater heat and thus more ion generation) or low power (less heat, less ions) operation of the device.
A preferably cylindrically shaped conductor may be disposed adjacent the heating element, upstream and/or downstream therefrom, and coupled to an appropriate node of the AC power source. The conductor presents a relatively modest electric field near the heater element that can greatly enhance the net outflow of positive ions or negative ions, or indeed substantially equally large numbers of each type of ions. A relatively high positive ion content in the output air flow is desired as it seems to condition a user""s hair, and to promote more rapid drying.
In a hair dryer or preferably in an industrial application, feedback may be included to automatically change polarity of charge at the grid to control net ion concentration in the output airflow, including substantially zero ion condition. In some commercial applications, it is desired to direct a stream of neutrally charged heated air at a specimen.